Certain 5-alkoxy-1,3,4-oxadiazol-2-ones with an ortho-substituted phenyl ring as substituent or with fused-on five- or six-membered rings have an anthelmintic (DE-A 26 04 110) and insecticidal action (DE-A 26 03 877, EP-B 0 048 040, EP-B 0 067 471).
Certain 5-phenoxy-1,3,4-oxadiazol-2-ones with an ortho-substituted phenyl ring as substituent show an endoparasiticidal action (EP-A 0 419 918).
Substituted 3-phenyl-5-alkoxy-3H-(1,3,4)-oxadiazol-2-ones with an inhibitory effect on hormone-sensitive lipase are disclosed in WO 01/17981 and WO 01/66531.